This work intended to show if there exist a relationship between the Rosin-Rammler and Swebrec distribution functions parameters and rock strength properties. The strengths parameters were determined in accordance to ISRM (2007) suggested methods. The two functions were used to reproduce sieving curves of different kinds of rocks fragmented on a laboratory scale using electric detonators. The curve fitting ability of Rosin-Rammler and Swebrec functions and the comparison of their fitting parameters with rock strength properties were assessed. The Rosin-Rammler parameters are shown to be interdependent while only parameters a and c of Swebrec function are related. The parameter b of Swebrec is related to the uniformity index, n and characteristic size, Xc of Rosin-Rammler function. By comparison, the parameters of the two functions show correlations with rock strengths properties (BTS, UCS, E and v). The uniformity index, n is related to all strength parameters involved in this study while the Swebrec c parameters did not show any relationship with rock strength. The Xc parameter of Rosin-Rammler is related to UCS, E and v. The and b parameters of Swebrec function are related to BTS, UCS and v and; BTS UCS and E respectively. In all cases the correlation coefficients are greater than 0.6 and can be fitted by power form law.


The Kuz-Ram equation in combination with Rosin- Rammler distribution function is the most widely used prediction model occurring in blasting literature. It has been a generally recognised method for giving a reasonable description of fragmentation of blasted rocks. Kuz-Ram prediction equation for the mean fragment size is given by a relation between the mean fragment size (Xm, cm) and the explosive quantity used per unit volume as a function of rock type categorised as medium hard rocks, hard and fissured rocks and weak rocks.

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